Duplex telegraph



B. TH0MPS0N an C. SBLDBN. 8 DUPLEX TBLBGRAPH.

No. 258,957. Patented June 6,1882.

'y 7W /MWW WQLX 1 UNITED STATES I PATENT OFFICE..

BENJAMIN THOMPSON AND CHARLES SELDEN, OF TOLEDO, OHIO.

DUPLEX TELEGRAPH.

SPECIFICATION forming part of Letters Patent 1\To.v 258,957, dated June 6, 1882,

Application filed July 10, 1879.

To all whom it may concern:

Be it known that we, BENJAMIN THOMPSON and CHARLES SELDEN, of Toledo, county of Lu- ,multiple telegraphs, by which means theI line may be balanced and the static discharge of the line fully neutralized; and it consists of the peculiar arrangement of the rheostat and the condenser, substantially as hereinafter described.

In the drawing, L B is a local battery; M B, a main battery; T, an ordinary duplex `transmitter; S C, a spark-coil; K, a Morse key; D R, a differential relay; Rheo., a set of resistance-coils; C, a condenser, and S R, a set of small resistance-coils.

When operator at key K closes his key local battery L B charges magnet of transmitter T and places main battery M B to line through points a. The battery, in passing to line, is rendered neutral on the differential relay D R by the adjustment of the rheostat Bheo., which is so adjusted that it will balance the line or oppose about the same resistance to the battery that the line offers to earth at distant end, and as the battery to the line passes in an opposite direction to the battery which goes through the rheostat the effect on the relay is neutralized, and while the line is charging the condenser C takes up its charge, and by carefully adjusting the condenser G its charge may be made to fully neutralize the static discharge from the line when it is placed to earth by operator at key K opening his key. The line being charged with a -lbattery, and the con denser G being also charged on No. l side with a -lbattery, a charge will be induced on No. 2 side of condenser C and bound there while the line is charged. Now, if the line be placed to earth, the -ldischarge ofthe line is made neutral on the dierential relay D R by the discharge from No. 2 side of condenser 2 side has a potential a little higher than the line it may be reduced by the coils S R. The

rheostat is so placed that the current shall go through it before passing through the relay.

The condenser arrangement differs from the arrangement of J. B. Stearns in the following particulars: In his arrangement of the condenser the discharge from No. l side only is utilized, the discharge from No. 2 side going directly to earth without exerting anyneutralizing or counterbalancing effect upon the static discharge from the line.

By our arrangement we utilize the discharge fromA both sides of the condenser, the discharge of No. 2 side tending to neutralize the static discharge of the line by flowing through the coils of the artificial line in relay D lt, while the discharge from No. 1 flows directly to the junction of the artificial line with the main line, and there divides, a portion going to earth and another portion to line. The latter portion, which flows to line, meets the static` discharge directly, and helps the discharge of No. 2 side in neutralizing its effects.

We are aware that the discharge of a conv denser has been utilized by J. B. Stearns and others for the purpose of neutralizing the effects of the static discharge in duplex working, and do not make any broad claim to con necting the condenser to the artificial line; but in every previous arrangement of which We are aware the condenser has been connected to the artificial line at a point between lthe coils of the di'erential relay and the IOO to said circuit ata point between the resistance andthe main-line circuits and the other ranged substantially in the manner and for end at a point between the resistance andthe the purposes set forth.

equating-coils, substantially as and for the BENJAMIN THOMPSON purpose described. s 5 2. The combination, with the equating-ciu (JHARLES SELDEN' cuit of the condenser C, connected to the same Attest: at a point between the key und the equating- WM. SCHULTZ, coils, und the lheostat-s Rheo. und S R, ull zu- E. H. RIIOADES. 

